1. Field of the Invention
The present invention relates to a method and apparatus for processing an image to perform data communication of input image data.
2. Related Background Art
A typical example of a conventional apparatus of this type is a facsimile apparatus. An original is read by a transmission-side apparatus, and data of the read original is encoded. The encoded data is transmitted to a reception-side apparatus. The reception-side apparatus expands the encoded data and outputs it. At this time, the read data on the transmission side is processed to reduce the quantity of data by some method (this processing is called compression hereinafter). The compressed data is transmitted and is decoded on the reception side.
In this conventional example, when data compression is used, received compressed image data is frequently expanded by means of predictive expansion.
One of such predictive techniques is pixel interpolation for interpolating data between pixels with reference to the decoded data of neighboring pixels. Since this pixel interpolation refers to the data of neighboring pixels, reference data are available at the edges of the image, and appropriate values cannot be obtained. For this reason, the edge portion of the decoded image is often deteriorated.
When the quantity of data is greatly increased upon transfer of one frame, as in a color image, it may be proposed to divide an original into several blocks and transmit it block by block. When the image data is decoded in this case, the edge portions of the image data of the respective blocks are deteriorated. When the divided image data blocks transferred to the reception side are synthesized on the reception side, distortion at the boundaries of adjacent blocks cannot be perfectly restored, resulting in inconvenience.
The following series of operations is generally performed in a conventional case. After an original is read by a transmission-side apparatus, image data of the read original is encoded in accordance with various schemes. The encoded data is transferred to a reception-side apparatus. The reception-side apparatus expands the reception data and outputs the expanded data.
In the above series of operations, when arbitrary processing is designated, the next processing cannot be started until the end of the arbitrary processing to cause a wait time. In particular, when color image data is to be processed, efficient processing is desirable because the quantity of data is greatly increased.